TESTING IN VACUO 10& 



Hering, however, afterwards showed that what Du Bois- 

 Reymond called ' positive polarisation ' was in reality 

 excitatory reaction. These excitatory effects are known 

 to be caused by either the anode or the kathode ; and I 

 have . - . demonstrated the fact that it is the difFeren- 

 tial excitability of a tissue which determines such uni- 

 directioned response. It is dijBficult, therefore, to see the 

 necessity of a new name for these phenomena. Dr. Waller 

 himself, however, ofFers the following explanation : 



" The great mass of living things, whatever else they 

 may give and take from their surroundings, take oxygen 

 and give carbonic acid ; they may live slowly or they may 

 live quickly — sluggishly smoulder or suddenly blaze. A 

 muscle at rest is smouldering ; a muscle in its contraction 

 is blazing ; the consumption of carbohydrate and the pro- 

 duction of CO^, never absolutely in abeyance, even in the 

 most profound state of rest, are sharply intensified when 

 the living machine puts forth its full power, and there is 

 then a sudden burst of heat, and an electrical discharge.*' 



This amounts to another way of saying that the cause 

 of the excitatory galvanometric effect is some explosive 

 dissimilatory change, a view which I have already shown 

 . . . to be quite untenable. I shall presently describe 

 experiments which will further show that galvanometric 

 responses, not to be distinguished from this, take place 

 when there is no 'possibility of any consumption of carbo- 

 hydrates or production of CO^. 



The fact, however, that the excitatory after-effects des- 

 •cribed disappear on the death of the tissue, has led Dr. Waller 

 to put forward the generalisation that this so-called " blaze- 

 current '' is the final distinction between living and non- 

 living matter. . . . Now, while it is certainly true 

 that the domain of physiological phenomena has not yet 

 been so thoroughly explored as that of the physical, it is 

 ■nevertheless equally true that no one could venture to 

 ■claim that even physical phenomena had up to the present 

 time been exhaustively studied. It is, then, somewhat 

 ^hazardous to declare that because a particular phenomenon 

 Jias not been observed to occur in inorganic matter, it is 



